Natural-gas gasoline



.Fan. 3. 19 5- 1523,3114

H. E. THOMPSON NATURAL GAS GASOLINE Original Filed May 31, 1925 Raw Gas Baf/er mmuummm teat HAROLD. E. THOMPSON, F CLENDENIN, WEST VIRGINIA, ASSIGNOR TO CIDE AND CARBON CHEMICALS CORPORATION, A CORPORATION OF NEW YORK.

NATURAL-GAS GASOLINE.

Original application filed May 31, 1923, Serial No. 642,624. Divided and this application filed may 10,

1924. Serial No. 712,348.

To all whom it may concern:

Be it known that I, HAROLD E. THOMPSON, a' citizen of the United States, residing at Clendenin. in the county of Kanawha and State of lVest Virginia, have invented certain new and useful Improvements in Natural-Gas Gasoline, of which the following is a specification.

The invention is a gasoline of novel chemical composition and physical characteristics. Such gasoline may be advan tageously produced by the process described and claimed in my copending application Serial No. 642.624 filed May 31, 1923, of which this application is a division. For a complete understanding of the subject matter claimed herein, the process referred to Will. now be described.

In Patent 1,429,17 5, issued to me on Sept.

12, 1922, I have described and claimed certain procedure for reducing the vapor pres-' sure of wild gasoline to such a value that a transportable and marketable liquid results, such reduction of vapor pressure being effected by the selective removal of those constituents of the wild mixture which have 'the strongest tendency to increase vapor pressure, whereby the requisite reduction of vapor pressure is obtained with the withdrawal of a minimum quantity of material, and the stab-1e salable residue, the gasoline, is produced in maximum quantity. In the patent, I have referred particularly to the stabilization of the wild product resultin from the well-known compression and oi absorption gasoline processes.

There is another natural gas gasoline process which has advantages that are now gaining general recognition, viz., the solidabsorbent process, in which the gas is brought into contact with an active solid absorbent, such as activated carbon, to remove I its gasoline constituents, the latter being then recovered from thesolid absorbent by steaming or other treatment adapted to cause the absorbed material to be liberated.

The solid-absorbent process as now usua1- 1y practised gives, like the older processes, an initial product which is much too wild to be marketed, and an additional treatment is required to stabilize this product. When the stabilizing process consists of weathering as practised prior to my invention, then the advantages of the solid-absorbent proccause with an increased absorption of gasoline constituents, there is also an increased absorption of more volatile substances, which go into the wild product and increase its vapor pressure excessively. The weathering treatment required to reduce the vapor pressure sufiiciently must then be very drastic, with the result that much of the true gasoline constituents are vaporized along with the undesired substances and lost. The inherent advantage of an unusually active absorbent is thus in a measure nullified. 1

Application Serial No. 642,624 covers a.v

species of my invention which difiers from the embodiment specifically claimed in my patent referred to, in that it describes and claims a process wherein wild asoline is produced from gas by the use 0 an active solid absorbent, and this product is stabilized by application of the .rinciples set out in the patent. The modi ed process will now be explained in connection with the accompanying diagrammatic drawing.

In the drawing, the natural gas, b means of suitable pi ing and valves, is rought into contact with solid absorbent in one or more of the absorbers A. The stri ped gas passes ofi' from the absorber to t 0 place of use.

When the material in an absorber has reached the desired degree of saturation, it is cut out of the gas current and its absorbed material is expelled, as by passing in steam (which may be superheated) from separating in the cooler is removed by an appropriate trap and the gas still under slight pressure is passed to a first condenser where its temperature is further reduced, say to about 70 F. This latter cooling results in. the condensation of a portion of the contained hydrocarbon material which collects in the receiver. marked Absorption gasoline receiver on the drawing, as a relatively quiet and non-volatile condensate.

The portion of the hydrocarbon material which is not liquefied in the first condenser is compressed to about 100 pounds per square inch, the compressed gas being again cooled to the temperature of cooling water in the second condenser, whereupon a further portion of hydrocarbonmaterial is liquefied and collected in the receiver marked Compression gasoline receiver on the drawing. This latter condensate, being formed, at a pressure of several atmospheres, will of course be more volatile or wild than .the absorption gasoline.

A portion of the hydrocarbon material will remain uncondensed even at a pressure of 100 pounds per sqdare inch and at the temperature of cooling Water, and. this material will escape through a pressure regulator set to hold the desired pressure in the compression gasoline receiver and may then be mixed with the stripped gas or utilized for any other purpose. The two liquid hydrocarbon fractions are then treated in a single rectifying column in accordance with the principles set forth in my patent referred to above.

The absorption gasoline being relatively non-volatile, requires but little rectification and is therefore introduced into the rectifying column at a point considerably removed from its top. The more volatile compression gasoline is introduced into the rectifying column at a higher point in order that it may be subjected to a more thorough.

rectification as it descends in the column.

The requisite cooling of thetop of the column is secured by the absorption of heat which takes place upon expanding the compression gasoline into the column, the pressure change being for example from 100 pounds per square inch to a pressure only slightly above barometric pressure.

The volatile hydrocarbons leaving the rectifying .column as vapors, and compris ing for example those constituents of natural gas which are more volatile than butane, will pass through a heat-exchanger wherein they serve to cool the incoming compression gasoline, and are then discharged into the stripped gas line or other place of use.

Except as noted, the operation of the rectifying column is identical with that disclosed in my patent referred to above, the vapor tension of the finished gasoline being readily adjusted by the rate at which heat is supplied to the heating coil of the kettle of the rectifying column. The character istics of the product being formed can be determined at any time by an observation of. the temperature of the material passing from the kettle to the rectifying column, and of the pressure at which the gaseous product of the rectifying column leaves theapparatus.

In the rectifying column, the wild mixture is separated into a vaporous fraction.

'and a liquid fraction which constitutes the final product, and the separation is so made that not more than one hydrocarbon individual occurs in substantial quantity in both fractions.

For a maximum yield of marketable gasoline, the material may be separated so that substantially all the butane enters the liquid while all more volatile hydrocarbons are boiled ofl". Of course, some of the butane may be removed from the liquid with the propane and other relatively volatile hydrocarbons, and a less volatile final product will result. It will usually be impossible to incorporate into the final product a substantial quantity of a hydrocarbon more volatile than butane, assuming that the product is to be transported and used as natural gas gasoline now is. The sum of the effects of the large quantity of butane and of the more volatile hydrocarbon would be too large to permit the material to pass any usual vapor-pressure specifications.

By excluding all hydrocarbons more volatile than butane from the final product, its

vapor pressure will sometimes remain within permissible limits when all thebutane in the gas treated is caused to enter the gasoline. That is to say, the gasoline produced is such cases is of acceptable quality, and a maximum yield is obtained, when all the butane of the gas'is incorporated into the gasoline. Full advantage may therefore be taken of the high activity of the absorbent. since the rectification treatment affords a means, not heretofore available, of selectively and quantitatively removing the hydrocarbons more volatile than butane.

Many of the natural gases now used for the recovery of gasoline contain a percentupward of 4( '54, which were free from propane andall more volatile hydrocarbons, and wh ch showed much lower vapor pressures than any gasolines of com arable. bu-' tane content heretofore fproduce The v'apor pressure of many these propane-free gasolines did not' substantially exceed 18' pounds at 100 F. Regardless of its vapor pressure, agasoline containing upward of 25% of butane and free from propane and 1 more volatile hydrocarbonsis a new composition so far as I am aware. v

- In a particular instance, a gasoline prm duced 1n accordance wlthmy inventlon contane and less volatile hydrocarbons, with hydrocarbons more volatile than butane absent. Despite this high butane content, the

vapor pressure of the product wasonly 13' pounds per square inch at 100. F.

It will be seen that by combining the rec-- tification steps with the solid-absorbent process, the entire butane content of a natural gas can often be incorporated into gasoline made therefrom without imparting an excessive vapor pressure to such gasoline,-

while if a product containing substances more volatile, than butane, or containing only a part of the butane, andno more volatile substances is desired, the combined process will produce the maximum quantity of such liquid of any given vapor pressure, or a minimum vapor pressure for any given yield of liquid. In this latter case, modifi-" 100 F. tained 46.2% butane, the balance being pencation of the final product is accomplished 3. As a new product, natural gas gasoline containing upward of 25% of butane and free from more volatile hydrocarbons.

4. As a new product, natural as gasoline containing upward of 25% of utane and freefrom more volatile hydrocarbons, and

having a vapor pressure not substantially in excess of 18 pounds per square inc 100 F.

5. As a new product, natural as gasoline containing upward of 40% of liutane and free from more volatile hydrocarbons.

- 6.. As anew product, natural gas gasoline containing upward of 40% of butane and having a vapor pressure not substantially in excess of '18 pounds per square inch at 100F.-

In testimony whereof, I aflEix my signature. HAROLD E. THOMPSON. 

